The present invention relates to pneumatic tires and, more particularly, to pneumatic tires designed for use on the drive axles of farm tractors and similar vehicles.
In order to enable tractors to pull plows or other like farming implements through the ground, it is necessary to provide on the tractor drive axles tires which develop sufficient traction in the soil under the encountered load conditions. Typically, this property is sought to be achieved by provision on the tire tread of a plurality of spaced-apart, generally transverse, discrete upstanding tread bars or "lugs" which are capable of biting into the soil in which the tractor is operated. A variety of such lug tread designs has been utilized or proposed in the art for purposes of increasing traction through improved biting capability and efficient explusion of earth from the deep recesses between the lugs. Such designs are also required to take into account the wear characteristics of the tread lugs.
The utilization of discrete lugs raised substantially above the base tread surface for improving the traction of tractor tires in generally encountered soil conditions is known to introduce tire and vehicle vibrations which affect ride comfort and vehicle stability, and impose stress on the drive axle. Vibration of this type is encountered when the tractor is used in the field, and is particularly noticeable when the tractor is driven on hard soil or paved surfaces as it occasionally must be, particularly at speeds above about ten miles per hour. Often, designers and manufacturers of pneumatic tractor tires face a compromise situation between traction capability on the one hand and minimized vibration/maximized stability on the other hand.